Combined accelerator pump and dashpot assembly for carburetors



Sept. 7, 1965 Filed June 30, 1961 R. W. M SEVENY COMBINED ACCELERATORPUMP AND DASHPOT ASSEMBLY FOR CARBURETORS 2 Sheets- Sheet 1 ROY W. M'SEVENY INVENTOR.

ATTORNEYS Sept 7, 1965 R. w. M SEVENY COMBINED ACCELERATOR PUMP ANDDASHPOT ASSEMBLY FOR CARBURETORS 2 Sheets-Sheet 2 Filed June 30, 1961 awWW :1 M 6 w m i R Y B 4 \6 l P 6 6 ATTORN EYS United States Patent3,204,935 COMBINED ACCELERATOR PUMP AND DASH- POT ASSEMBLY FORCARBURETORS Roy W. McSeveny, Garden City, Mich., assignor to Ford MotorCompany, 'Dearborn, Miclr, a corporation of Delaware Filed June 30,'1961,:Ser. No. 12150 46 2 Claims. (0!. 261-34) This invention relatesto a combined accelerating pump and dashpot assembly for use invehicular carburetors.

Rapid opening or closing of the throttle valve of a vehicular carburetorproduces undesirable engine performance characteristics. Upon suddenopening of the throttle valve, the engine will hesitate or stall unlessan increased amount of fuel is supplied immediately. Accelerating pumpswhich spray additional fuel into the carburetors throttle passage areutilized to provide the initial increase of fuel requirements. If thethrottle valve is closed too rapidly, the engine will also stall. Forthis reason, vehicular carburetors often incorporate some form ofdashpot mechanism to retard the rate of throttle closing. Frequently, asingle carburetor will incorporate both an accelerating pump and adashpot. Although the accelerating pump and dashpot may be controlled bya common member, they are separate and otherwise independent units.

It is an object of the present invention to provide a unitary carburetoraccelerating pump and dashpot to permit a compact carburetorconstruction.

A carburetor incorporating the instant invention includes areciprocating member operated in response to the throttle controllinkage. Two coaxially disposed pumps are operated in response tomovement .of the reciprocating member. Suitable conduits and checkvalves allow each pump to be charged with fluid from the carburetor fuelbowl. One pump acts as an accelerating pump by discharging fuel throughthe carburetor jets during rapid opening of the throttle valve. Theother pump draws fuel from the fuel bowl through a restricted orifice tofunction as a dashpot when the throttle is rapidly closed.

In an embodiment of the invention, a check valve in the inlet conduit ofthe dashpot is prevented from seating during a portion of the pumpingstroke. This shunts flow from the orifice during a portion of the stroketo shorten the effective stroke of the dashpot. This allows theaccelerating pump and dashpot to operate over different length strokes.

Further objects and advantages of this invention become more apparent asthis description proceeds, particularly when considered in conjunctionwith the accompanying drawings, wherein:

FIG. 1 is a top plan view of .a vehicular carburetor incorporating anembodiment of the instant invention.

FIG. 2 is a side elevational view of the carburetor shown in FIG. 1 withthe carburetor top plate removed.

FIG. 3 is a cross sectional view taken along line 33 of FIG. 1 with thecarburetor top plate removed.

FIG. 4 is a cross sectional view taken along line 44 of FIG. 1 with thecarburetor top plate removed.

FIG. 5 is a cross sectional view in part similar to FIG. 4 showinganother embodiment of the invention.

Referring now in detail to the drawings, there is shown generally at 11a carburetor embodying the present invention. The body 12 of carburetor11 is formed with a fuel bowl 13 and throttle passage 14. A float 15controls the level of the fuel in fuel bowl 13. A throttle valve 16 isrigidly secured to a throttle valve shaft 17. Throttle valve shaft 17 isrotatably supported by can buretor body 12 to position throttle valve 16in throttle 3,204,935 Patented Sept. 7, 1965 ice passage 14 and controlthe flow of fuel air mixture therethrough. The angular position ofthrottle valve 16 in throttle passage 14 is controlled by the throttlecontrol link 18 which is rigidly secured for rotation with throttlevalve shaft 17. Link ,18 is actuated in response to the acceleratorlinkage (not shown). The construction thus far described is conventionaland forms no part of the present invention.

An embodiment of the accelerating pump and dashpot of the instantinvention is shown in detail in FIGS. 3 and 4. The accelerating pump isindicated generally at 19. The dashpot is shown generally at 21.Accelerating pump 19 and dashpot 21 include a common actuating member,rod 22. Rod 22 is supported for reciprocation in the bore 23 formed incarburetor body 12. Accelerating pump 19 is of the diaphragm type andincludes a flexible diaphragm 24 overlying the mouth of a cylindricalcavity 25 formed in carburetor body 12. Diaphragm 24 is held in place bythe annular member 26 secured to carburetor body 12 as by the bolts 27.Rod 22 passes through an aperture formed in the center of diaphragm 24.The rigid washers 28 support the center of diaphragm 24 and rigidlysecure the center of diaphragm 24 to rod 22 in the known manner.

Fuel may flow from fuel bowl 13 to cavity 25 through the passage 29formed in carburetor body 12. The ball check valve 31 prevents fuel flowin a reverse direction. A bolt 32 threaded in the carburetor body 12permits replacement of a ball 31. Accelerating pump 19 dischargesthrough the passage 33 and discharge nozzle 34 into carburetor throttlepassage 14. A ball check valve 35 positioned in passage 33 prevents theentry of air into cavity 25.

Dashpot 21 includes rod 22 and reduced diameter piston portion 36 formedon the end of rod 22. The

innermost portion of bore 23 functions as a cylinder for rod 22 andpiston portion 36. Fuel may enter bore 23 from fuel bowl 13 through ametered orifice 37. Another fuel passage 38 connects bore 23 and fuelbowl 13. A ball check valve 39 is positioned in passage 38 to preventfiow of fuel through passage 38 when rod 22 moves to the left. Ball 39is retained in passage 38 by the aperture plug 41.

Rod 22 is actuated in response to throttle control link 18. For thispurpose, a lever 42 is rotatably supported on throttle Valve shaft 17. Acoil spring 43 encircles shaft 17 and has its opposite end secured tolever 42 and link 18. A rod 44 interconnects lever 42 and a lever 45pivotally supported by the portion 46 of annular member 26. Aperturesare formed in levers 42 and '45 through which rod 22 passes. A coilspring 47 contained between the nut 48 and lever 45 urges lever 45 intocontact with the shoulder 49 formed on rod 22. In this way, pivotalmovement of lever 45 is translated into reciprocatory movement of rod 22and motion may be transmitted between throttle control link 18 and rod22.

Operation Clockwise movement of throttle control link 18 to openthrottle valve 16 is transmitted through coil spring 43 to lever 42 andthis motion is translated into movement of rod 22 to the right as seenin FIG. 4. This causes accelerating pump 19 to discharge fuel throughpassage 33 and nozzle 34 into throttle passage 14. During this movement,ball check valve 31 prevents flow of fuel from cavity 25 to fuel bowl13. Dashpot 21 merely pumps fuel from bore 23 into fuel bowl 13 throughorifice 37 and passage 38. Ball check valve 39 is open during thismovement so there is no fluid resistance to opening of throttle valve16. Once rod 22 completes 3 throttle valve 16 without accompanyingmovement of rod 22.

Counterclockwise movement of throttle control link 18 to close throttlevalve 16 causes rod 22 to move to the left once the lost motionpermitted by spring 43 is taken up. During this movement, ball checkvalve 35 closes and ball check. valve 31 opens allowing acceleratingpump 19 to be charged with fuel from fuel bowl 13. Ball check valve 39also closes so fuel can be drawn into bore 23 by rod 22 only throughorifice 37. The fluid resistance created retards the movement of rod 22and, in turn, the rate of closing of throttle valve 16.-

Frequently, it is desirable to have the dashpot operate over a shorterstroke than the accelerating pump does.

This is permitted by the construction showing in FIG. 5. Theaccelerating pump shown in FIG. 5 is identical to that shown in FIGS. 3and 4 and further description is deemed unnecessary.

The dashpot assembly of the embodiment of FIG. 5 is indicated generallyat 61. The metered orifice 62 permits restricted fuel flow between fuelbowl 13 and bore 23. A passage 63 also permits flow between bore 23 andfuel bowl 13. Passage 63 is axially aligned with rod 22 and includes aball check valve 64. The coil spring 65 normally urges ball check valveinto a seated position in which fuel flow through passage 63 isobstructed.

As the throttle valve 16 is opened, rod 22 moves to the right in amanner previously described. This increases the fuel pressure in bore 23and spring 65 will yield to permit check valve 64 to open as soon as rod22 commences movement. Continued movement of rod 22 to the right bringsthe projection 66 formed on the end of rod 22 into contact with ball 64.The diameter of rod 66 is sufficiently small to pass through the passage63. As the throttle valve 16 is closed, rod 22 commences to move to theleft. Initial movement of rod 22 to the left produces no fluidresistance since projection 66 prevents check valve 64 from seating.There is sufficient clearance between projection 66 and passage 63 topermit free fuel flow. Under this condition, fluid may flow freely fromfuel bowl 13 to bore 23 through passage 63. After rod 22 has moved tothe left suffi ciently to free check valve 64 from the action ofprojection 66, the check valve will seat. Fluid must then flow to bore23 through restricted orifice 62. The resulting fluid resistance retardsthe rate of further closing of the throttle valve 16. The effectivelength of the stroke of the dashpot 61 may be regulated by the length ofthe projection 66.

It is to be understood that the invention is not to be limited to theconstruction shown and described, but

that various changes and modifications may be made ciprocating member,driving means operatively connecting said throttle control linkage andsaid reciprocating member for interrelated movement, first and secondpump means including first and second fuel impelling means affixed tosaid reciprocating member, first means communicating fuel flow from saidfuel bowl to said first pump means, second means communicating fuel flowfrom said first pump means to said throttle passage upon movement ofsaid reciprocating member for its full travel in a directioncorresponding to opening of said throttle valve, third meanscommunicating fuel flow between said second pump means and said fuelbowl, and means restricting fuel flow between said second pump means andsaid fuel bowl movement of said reciprocating member for only a portionof its movement in a direction corresponding to closing of said throttlevalve.

2. In a carburetor having a fuel bowl, a throttle passage, a throttlevalve and throttle control linkage, a re ciprocating member, drivingmeans operatively connecting said throttle control linkage and saidreciprocating member for interrelated movement, first and second pumpmeans operated by said reciprocating member, first means communicatingfuel flow from'said fuel bowl to said first pump means upon movement ofsaid reciprocating member in a first direction corresponding to closingof said throttle valve, second means communicating fuel flow from saidfuel bowl to said second pump means upon movement of said reciprocatingmember in said first direction, said second means being constructed toretard movement of said reciprocating member in said first direction byrestricting fuel flow therethrough, third means communicating fuel flowfrom said first pump means to said throttle passage upon movement ofsaid reciprocating member in a second direction corresponding to openingof said throttle valve, fourth means communicating fuel flow betweensaid second pump means and said fuel bowl, valve means in said fourthmeans preventing fuel flow from said fuel bowl to said second pump meansupon movement of said reciprocating member in said first direction, andmeans preventing closing of said valve means upon movement of saidreciprocating member in said first direction for a portion of itsstroke.

References Cited by the Examiner UNITED STATES PATENTS 1,844,73 8 2/32Aseltine.

1,954,536 4/34 Prentiss.

1,999,334 4/ 35 Mallory.

2,047,899 7/3 6 Aseltine.

2,236,560 4/41 Bancroft.

2,619,333 11/52 Carrey.

2,703,705 3/55 Boller.

2,968,476 1/61 Stoltman 267-1 HARRY B. THORNTON, Primary Examiner.

EUGENE BLANCHARD, RONALD WEAVER,

Examiners.

1. IN A CARBURETOR HAVING A FUEL BOWL, A THROTTLE PASSAGE, A THROTTLE VALVE AND THROTTLE CONTROL LINKAGE, A RECIPROCATING MEMBER, DRIVING MEANS OPERATIVELY CONNECTING SAID THROTTLE CONTROL LINKAGE AND SAID RECIPROCATING MEMBER FOR INTERRELATED MOVEMENT, FIRST AND SECOND PUMP MEANS INCLUDING FIRST AND SECOND FUEL IMPELLING MEANS AFFIXED TO SAID RECIPROCATING MEMBER, FIRST MEANS COMMUNICATING FUEL FLOW FROM SAID FUEL BOWL TO SAID FIRST PUMP MEANS, SECOND MEANS COMMUNICATING FUEL FLOW FROM SAID FIRST PUMP MEANS TO SAID THROTTLE PASSAGE UPON 